CHANNELS

Scientists closer to universal flu vaccine after swine flu pandemic

Scientists may have discovered the “blueprint for developing a universal flu vaccine" after using the 2009 swine flu pandemic as a natural experiment to study why some people seem to resist severe illness.

They found that those who avoided severe illness had more CD8 T cells, a type of virus-killing immune cell, in their blood at the start of the pandemic.

After the outbreak in 2009, Professor Lalvani and his team, from the National Heart and Lung Institute at Imperial College London, rapidly recruited 342 staff and students at Imperial to take part in a revolutionary study.

As part of the trials, the volunteers were asked to donate blood samples and nasal swabs.

They were also sent emails every three weeks asking them to fill in a survey about their health. If they experienced flu symptoms, they took a nasal swab and sent it back to the lab.

They found that those who fell more severely ill with flu had fewer CD8 T cells in their blood. Those who caught flu, but had no symptoms or only mild symptoms, had more of these cells.

Research published today in Nature Medicine suggests that a vaccine which helps the body to produce preventative CD8 T cells could effectively protect against different strains of flu viruses, including dangerous cross-species strains from birds and pigs.

Professor Ajit Lalvani from the National Heart and Lung Institute at Imperial College London, who led the study, said: “New strains of flu are continuously emerging, some of which are deadly, and so the Holy Grail is to create a universal vaccine that would be effective against all strains of flu”.

The current flu vaccines are designed to recognise and respond to specific structures on the flu virus, also known as antigens. As these antigens evolve and mutate, viruses with different surface structures evolve, rendering the vaccines obsolete.

As a result, new vaccines have to be developed every year as scientists desperately try to keep up.

A universal vaccine would therefore be invaluable, and protect vulnerable members of society from a common yet dangerous virus.

Previously, experimental models predicted that T cells could offer universal protection against flu-symptoms. However, this is the first time the idea has been tested on humans.

Professor Lalvani said, “The immune system produces these CD8 T cells in response to usual seasonal flu. Unlike antibodies, they target the core of the virus, which doesn’t change, even in new pandemic strains.

"The 2009 pandemic provided a unique natural experiment to test whether T cells could recognise, and protect us against, new strains that we haven’t encountered before and to which we lack antibodies".

“Our findings suggest that by making the body produce more of this specific type of CD8 T cell, you can protect people against symptomatic illness. This provides the blueprint for developing a universal flu vaccine".

“We already know how to stimulate the immune system to make CD8 T cells by vaccination. Now that we know these T cells may protect, we can design a vaccine to prevent people getting symptoms and transmitting infection to others.

"This could curb seasonal flu annually and protect people against future pandemics”.